function s1_generate_a_series_of_files(){
	for i in {1..100};do echo $i>/tmp/new_file$i;done
}
function s2_list_4_files_in_long_format_about_account_and_group(){
	ls -l /etc/{passwd,shadow,group,gshadow} | sort -d
}
function s3_find_items_related_to_given_username(){
	grep -h $1 /etc/{passwd,shadow} | sort -d
}
function s4_find_items_related_to_given_group_name(){
	grep -h $1 /etc/{group,gshadow} | sort -d
}
function s5_create_groups_for_given_group_names(){
	groupadd rnd && groupadd itoperation
}
function s6_create_users_and_set_their_group_as_required(){
	useradd -G rnd adam && useradd -G rnd bob && useradd -G itoperation calvin && useradd -G itoperation david && useradd -G rnd edward
}
function s7_change_users_shell(){
	usermod -s /usr/bin/sh adam && usermod -s /usr/bin/sh edward
}
function s8_set_password_change_policy(){
	passwd -n 10 -x 60 -w 10 adam
    passwd -n 10 -x 60 -w 10 bob
	passwd -n 10 -x 60 -w 10 david
	passwd -n 10 -x 60 -w 10 calvin
	passwd -n 10 -x 60 -w 10 edward	
}
function s9_set_password_for_five_users(){
	usernames=("adam" " bob" "calvin" "david" " edward")
	echo "${usernames[0]}:NewPassword1" | chpasswd
	echo "${usernames[1]}:NewPassword2" | chpasswd
	echo "${usernames[2]}:NewPassword3" | chpasswd
	echo "${usernames[3]}:NewPassword4" | chpasswd
	echo "${usernames[4]}:NewPassword5" | chpasswd
}
function s10_lock_bobs_password(){
	usermod -L bob
}
function s11_include_adam_into_wheel_group(){
	sudo usermod -aG wheel adam
}
function s12_change_files_permission(){
for file in $(ls new_file*); do  
    if [ $(echo $file | grep -o '[0-9]\{3\}$') ]; then 
        chmod 440 $file  
    fi  
done
}
